降雨条件下拓宽路堤稳定性数值分析

基于非饱和渗流理论，在有限差分软件FLAC3D渗流模块的基础上，采用内置FISH语言自编程序实现了降雨条件下拓宽路堤上饱和-非饱和渗流过程的模拟，进而分析了降雨入渗对拓宽路堤孔隙水压力和饱和度的影响，以及土工格栅加筋和填料渗透系数对降雨条件下拓宽路堤稳定性的影响.研究结果表明：降雨初期路堤土体基质吸力迅速降低，边坡最先达到饱和状态，形成暂态饱和区；考虑降雨入渗影响时，拓宽路堤安全系数明显减小，土工格栅加筋可有效减小降雨入渗对拓宽路堤稳定性的影响；新路堤填料渗透系数对降雨条件下拓宽路堤稳定性的影响较大，实际工程中应保证路堤填土的压实度并采取边坡防护措施以减小雨水入渗的影响.
The simulation of saturated and unsaturated seepage under rainfall conditions was carried out by self-programming system using the built-in FISH language based on the seepage module of finite difference software FLAC3D and the unsaturated seepage theory.The pore water pressure and degree of saturation of the widened embankment under rainfall conditions were analyzed.The effects of geogrid reinforcement and permeability coefficient on the stability of the widened embankment were also investigated.The results show that the soil matric suction decreases rapidly and the slope reaches to saturated state and forms the transient saturated zone firstly.The safety factor of the widened embankment decreases obviously,considering the effect of rainfall infiltration.The geogrid reinforcement reduces the effect of rainfall infiltration on the stability of the widened embankment.Meanwhile,the permeability coefficient of the newly constructed embankment has large effect on the stability of the widened embankment under rainfall conditions.In practical engineering,the degree of compaction of the embankment fill should be guaranteed and the measures of slope protection should be taken to reduce the effect of the rainfall infiltration.